Computer networks typically provide a physical interconnection between different computers to allow convenient exchange of programs and data. A plurality of connectivity devices, such as switches and routers, interconnect each user computer connected to the network. The connectivity devices maintain routing information about the computers and perform routing decisions concerning message traffic passed between the computers via the connectivity devices. Each connectivity device, or router, corresponds to a network routing prefix (prefix) indicative of the other computers which it has direct or indirect access to. Therefore, data routed from one computer to another follows a path through the network defined by the routers between the two computers. In this manner, the aggregation of routers in the network define a graph of interconnections between the various computers connected to the network.
In a graphical representation, therefore, such a network may be conceived as a graph of nodes between computers. The graph defines one or more paths between each of the computers connected to the network. The routers, therefore, define nodes in a network, and data travels between the nodes in a series of so-called “hops” over the network. Since each router is typically connected to multiple other routers, there may be multiple potential paths between given computers. Typically, the routing information is employed in a routing table in each router which is used to determine a path to a destination computer or network. The router makes a routing decision, using the routing table, to identify the next “hop,” or next router, to send the data to in order for it to ultimately reach the destination computer. However, network problems may arise which render routers and transmission paths between routers inoperable. Such failures effectively eliminate nodes or hops in the graph, should such failure be detected by the control plane, defined by the network, therefore interfering with data traffic which would have been routed over the affected paths.